I. Field of the Invention
This invention relates, in general, to fluid operated, expansible chamber cylinders and, more specifically, to position sensors for fluid operated, expansible chamber cylinders.
II. Description of the Prior Art
Fluid operated, expansible chamber cylinders find widespread usage in machine and other manufacturing equipment. Such cylinders, typically of the compressed air or hydraulic operated type, utilize axial movement of a piston housing within the cylinder to effect a desired action of a working component attached to the external end of a piston rod connected to the piston. Control valves operated by sensors, such as limit switches, are employed to control such cylinders by causing the desired directional movement of the piston at the correct time in the machine sequence.
Since it is often necessary to know when the piston has moved to the fully extended or retracted travel position before the next step in the machine sequence can take place, limit switches have been used to contact the external end of the piston rod or the connected work component at the end of piston travel. However, the use of such externally mounted limit switches encountered several problems since such switches are susceptible to damage in the crowded mechanical environment in which they are located. Furthermore, externally mounted limit switches are bulky and require special mounting arrangements which must be added to the machine.
To overcome these problems, sensors or limit switches have been mounted directly on fluid operated cylinders and sense the position of the piston within the cylinder. Such sensors are contained within a housing mounted directly on the cylinder, typically by fasteners, such as screws or bolts, and extend through a bore formed in the cylinder into proximity with the piston or piston rod.
While the use of sensors mounted directly on the cylinder eliminate many of the problems associated with externally positioned limit switches, they are not without their own disadvantages. Since such sensors are mounted in a single fixed position on the cylinder, the wiring or other connections to remotely located control equipment exit the housing from only one direction or side. This places considerable restraints on the machine designer in mounting a fluid operated cylinder on a machine since he must provide space for such connections in the oftentimes crowded machine environment.
Thus, it would be desirable to provide a fluid operated cylinder position sensor mounting apparatus which overcomes the problems associated with previously devised position sensor mounting apparatuses. It would also be desirable to provide a position sensor mounting apparatus for fluid operated cylinders which permits wiring or other connections leaving the sensor housing to be located in any desired orientation. Finally, it would be desirable to provide a position sensor mounting apparatus for fluid operated cylinders which can be located in any position or angular orientation on the cylinder without requiring removal and reattachment of the sensor on the cylinder.